'Greenstone' definitions:

Definition of 'Greenstone'

From: GCIDE

Greenstone \Green"stone`\ (gr[=e]n"st[=o]n`), n. [So called from a tinge of green in the color.] (Geol.) A name formerly applied rather loosely to certain dark-colored igneous rocks, including diorite, diabase, etc. [1913 Webster]